ISSN:
1432-0630
Keywords:
PACS81.15.Fg; 68.55.Nq; 71.25.Mg; 82.65.My
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Abstract. Amorphous carbon (a-C) films obtained by pulsed-laser ablation of graphite have been investigated by X-ray Absorption Spectroscopy (XAS). The onset of $1s\rightarrow\sigma^{*}$ transitions in the films lies in the gap between the $\pi^{*}$ and $\sigma^{*}$ bands in graphite and very close to the absorption edge of diamond, indicating a high content of $sp^{3}$ hybridization. A sharp feature at this onset is observed and assigned to a core exciton in $sp^{3}$ -hybridized disordered C atoms. Its shift of 0.5 eV with respect to the core exciton in diamond is probably due to a higher localization of the excited electron induced by disorder. A small peak coming from C-H bonds at the surface is observed and its intensity increases with the amount of $sp^{3}$ -hybridized atoms in the sample. This can be easily explained by associating a higher amount of dangling bonds at the surface to a higher $sp^{3}$ content. Polarization-dependent XAS measurements show that the angular distribution of these C-H bonds has a mean value close to the normal to the surface.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s003390050175
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